1. Field of the Invention
The present invention relates to the field of shelving systems for circuit cards, and more particularly, to shelving systems of communications networks components.
2. Description of the Related Art
A data communications network allows communication between multiple communicating entities over one or more data communications links. High bandwidth applications supported by these networks include streaming video, streaming audio, and large aggregations of voice traffic. In the future, these demands are certain to increase. To meet such demands, an increasingly popular alternative is the use of lightwave communications carried over fiber optic cables. The use of lightwave communications provides several benefits, including high bandwidth, ease of installation, and capacity for future growth.
The synchronous optical network (SONET) protocol is among those protocols designed to employ an optical infrastructure and is widely employed in voice and data communications networks. SONET is a physical transmission vehicle capable of transmission speeds in the multi-gigabit range, and is defined by a set of electrical as well as optical standards. A similar standard to SONET is the Synchronous Digital Hierarchy (SDH) which is the optical fiber standard predominantly used in Europe. There are only minor differences between the two standards. Accordingly, hereinafter any reference to the term SONET refers to both SDH and SONET networks, unless otherwise noted.
Referring to FIG. 1, a typical SONET network requires a shelf 100 for printed circuit boards holding interfaces. A printed circuit board (PCB), such as PCB 120 required for network communication includes optical connections as well as hard-wired connections. A network shelf must accommodate different sizes of PCBs in each vertical column. A problem with the typical shelf system is that smaller PCBs with optical connectors are often damaged upon installation. Further, electrical connectors typically suffer from pin stubbing and bending during installation into a typical shelf. Another problem associated with the typical shelf system is that combining different size PCBs in a single vertical column is difficult for most shelf systems and impossible for other shelf systems. Thus, the typical shelf does not efficiently use available space. One known method of permitting different sized PCBs in a single vertical shelf is to provide removable card guides that change the size of the modules before PCBs are installed. Thus, a physical change to the shelf system is required each time a reconfiguration of PCBs is desired.
What is needed is a shelf system that accommodates reconfigurations without requiring a physical redesign of the shelf and further protects electrical and optical components from damage.
In accordance with the present invention, a railing system for printed circuit boards, an apparatus and method advantageously allow modular arrangements of printed circuit boards (PCBs) in a shelf and simultaneously maximizes space in the shelf by providing rails on the PCBs that are slidably connectable with card guides in the shelf. More particularly, the railing system includes a PCB having two sides, at least one of the sides with electronic components disposed thereon, and at least one rail secured to the PCB, the rail being perpendicular to the sides of the PCB, wherein the rail permits insertion of the PCB into a shelf outfitted with one or more guides for securing the rail and the PCB within the shelf by suspension from the rail and independent of further support. The rail in combination with the one or more card guides provide a crude alignment for mating the electrical components on the PCB with connectors disposed in the shelf. Further, the rail in combination with the one or more card guides conserve space within the shelf by permitting contiguous PCB installation within the shelf. In one embodiment, the railing system provides that the PCB has two sides and the at least one rail includes two rails, one on each side of the PCB. In an alternate embodiment, the railing system provides that each side of the PCB is coupled to two rails, the rails being secured to the PCB with screws. The railing system further provides that the size of the PCB is variable, the one or more guides accommodating the variability. More specifically, the one or more guides include a plurality card guides disposed within the shelf, each card guide being a distance X from a next card guide, wherein a plurality of PCBs having a variety of sizes with the at least one rail are insertable into the card guides at multiples of X. For example, in one embodiment the size of the PCB varies from a 2.490 inch size, a 5.002 inch size, a 10.036 inch size and a 20.104 inch size. Further, the railing system allows both electrical and optical components disposed on the PCB to be configured for a synchronous optical network (SONET) communication system.
One embodiment is directed to an apparatus including at least one rail designed to be secured to a printed circuit board (PCB) at two points on the PCB, the PCB having two sides, at least one of the sides with electronic components disposed thereon, the rail being installable perpendicular to the sides of the PCB, wherein the rail permits insertion of the PCB into a shelf outfitted with one or more guides for securing the rail and the PCB within the shelf by suspension from the rail. In one embodiment, the rail includes a first rail and a second rail, the first rail including two threaded areas for accepting two screws for securing the first rail to the PCB, and the second rail including two areas defining holes for inserting the two screws and threading the two screws into the first rail and the second rail. In another embodiment, each threaded area mates with an area defining a hole on the PCB and to one of the two areas defining holes on the second rail thereby allowing a screw to be inserted into the hole on the second rail, through the PCB and to be screwed into the threaded area. In another embodiment each PCB has two sets, each set including the first rail and the second rail, the first set attached to an upper portion of the PCB and the second set attached to a lower portion of the PCB. The first rail and the second rail of each set are U-shaped, the first rail of each set extending outward from the PCB farther than the second rail of each set. Each rail is a U-shaped stainless steel with a 6 gauge thickness. In one embodiment, the rail is one of four rails disposed on the PCB, and the PCB is one of a plurality of sizes.
Another embodiment of the invention is directed to an apparatus including a shelf for receiving at least one printed circuit board (PCB), the PCB being coupled to at least one rail; and at least one card guide disposed on an interior side wall of the shelf, the at least one card guide permitting insertion of the PCB into the shelf and securing the rail and the PCB within the shelf by suspension from the rail in the card guide.
Another embodiment is directed to a method for a railing system for printed circuit boards. The method includes providing a shelf for receiving at least one printed circuit board (PCB), the PCB being coupled to at least one rail, and providing at least one card guide disposed on an interior side wall of the shelf, the at least one card guide permitting insertion of the PCB into the shelf and securing the rail and the PCB within the shelf by suspension from the rail in the card guide.